Pay video program broadcasting and pay transmission services have recently started with the introduction of so-called scramble technology in various fields such as satellite television broadcasting and CATV systems. Similar technologies have also been adopted for packaged video programs such as video cassette tapes with respect to copyguard and copyright protection.
An example of audio signals in video programs recorded on cassette tapes (such as VHS and 8-mm tapes) which require scrambling is explained next. Passenger aircrafts are increasingly provided with liquid crystal television sets facing each seat, depending on the class of the seat. There is a system to allow the passenger to select a preferred program from the menu of the tape provided and play it back. If this cassette tape is removed by the passenger for their own use, there is a danger that the programs recorded on the cassette tape may be copied. Since airlines often provide new programs before or immediately after they are released to cinemas, to provide better service to passengers, copying of such new programs risks causing a serious problem. Thus, audio signals are scrambled before recording onto the tape so that sound cannot be reproduced with standard playback units.
Several audio signal scrambling and descrambling technologies have already been introduced. They all require large-scale circuitry and operation processing to be built into the main body of the video playback unit. For example, an audio scrambling and descrambling process may need to be incorporated in conventional signal processing for scrambling and descrambling the audio signal in VHS and 8-mm video tapes. This requires significant efforts Including redesigning of existing hardware (LSIs, ICs), large-scale software modifications, and testing and verification of system operations based on these changes.